non-metal/barrel downdraft chambers

[patamos]

I'm looking to build a 6" J-feed system with a non-metal downdraft chamber, and am pondering the best way to go about it.  I've seen many pictures of such units operating and am wondering if anyone has experiences/feedback/advice to share. ??

B.T.W.:  In an effort to free up photo space for more recent builds, I have moved all photos of this build to:
s895.photobucket.com/user/patamos/library/?sort=2&page=1

BEWARE of pop ads on that site.  Even minimizing them can freeze your computer into a no exit situation.

well being


pat 

[Donkey]

Sure..
Though if you're a little more specific about the purpose, maybe we can brain-storm your particular solution.
Do you just want a neat looking masonry mass or are you looking to pipe the heat somewhere in particular?

[satamax]

technologieforum.forumatic.com/viewtopic.php?f=19&t=27

batchrocket.hostoi.com/html/foto.html

[Robert]

Hey i like this bell stove with two layers. I have some question though. Why is he using the insulation beetwen first layer and second layer of the bricks? Is this will not make a heat transfer lower to the room? It is insulation isn`t it?

[peterberg]

It's called a double skinned stove as opposed to a single skin. The insulation between the skins is superwool, serving three purposes. The first is to ensure the outer skin isn't touching the inner skin, it allows for expansion of the core so it's an expansion joint and third it will even out any hotspots, so the outer skin will be mostly uniform in temperature.

[Robert]

looks i have to learn so many things more. especially about the heat transfer things. Just as i was understanding the space beetwen the two layers of bricks will act as an insulation especially filled with superwool. Than i would imagine that it limits the heat transfer from the core to the outer layer of the stove and thus limiting the radiation. But it looks like this is not the problem. Thanx Peter for explaining everything so nicely here.

[patamos]

Thanks Donkey, Peter and Robert,

I have been posing questions on two other threads as i commence this build.  The main conversation thus far is happening at:

donkey32.proboards.com/thread/1064/widening-flue-turns-matter?page=1&scrollTo=9784

Where MatthewWalker and Pinhead are helping tons.  I am really jazzed by the idea taking shape.
I'm also connecting in with Robert's thread about J-feed trip wire and we are looking at ways (learning from Peter) to shape/accommodate P-channel and door closures.  I'm still catching up on many a past thread so am very grateful for people offering to explain through the gaps in my awareness.

I haven't go the sketch up figured out yet, but if you imagine a 6"x12" downdraft off one side of the heat riser morphing into a 5+' single skin brick flue just inside the front face of a curved 7' bench, then spilling into a larger bench bell behind the initial flue - ala half barrel bells, but with reclaimed brick and cobb.  Looking to keep the outside front vertical wall thinnish (but tight with fiberglass mesh in the outer cob) so that it radiates a fair bit of what would otherwise happen with the barrel. 
Exit flue from bell down low behind the heat riser.  Bypass flue T-s off from bottom of downdraft.  Damper above then T-s into vertical exhaust.
Essentially this is a part flue run part bell hybrid.  Waterfall into fast running stream into big eddy pool.
Also, funnily enough, it blows wide open my question of "does widening the flue turns matter?"
Maybe that is reason enough to post the journey on that thread.

I'll send pics tomorrow with the basic layout dry-stacked on the ground.
Any feedback is welcome and much appreciated.





 
 

[Robert]

great keep posting the pictures i am following your build

[patamos]

Okay forum wiz-ards, Here is the basic idea
A 6" (or 7") J-feed system with all the down draft exiting to one side.  The preferred location is such that the heater core will be close to wooden stair risers.  I am isolating well with clay perlite both sides of metal and/or backer board.  But for this reason, along with aesthetic preference of the clients, i am doing other than metal barrel.
In these pics you can hopefully see the double stacked firebricks where the downdraft chamber will lead away into a partial flue that leads into a bell.  The heat riser will be located about where the back of the existing little stove is.
A little harder to discern is the bypass flue near the bottom of the down draft in the foreground and the exhaust flue from the bell in the background.  I'll likely stick with round elbows and careful cobbing. 
The damper will be between the 90 elbow bypass feeding off the downdraft chamber and the T with a 90 above.
Primary ash pit at the front of the down draft chamber (beside the stove)
I have been hoping to keep this down draft and primary flue a single skin unit but am thinking i might be better to double skin the front face of the bench at least to where the flue opens into the bell.  I have a fair bit of 1/8" ceramic felt to play with.  Can even double it up

The third pic shows an idea for baffles which are also placed to support the joints between 2'x2'x2" concrete pavers.
Thinking also of flue/bell cleanout where my toes are pointing.  Bell flue exit is in the top right corner of the pic.


All feedback is welcome and much appreciated.

 

[Robert]

cool. i will not tell much just that i have seen something like this made by Sjang van Daal.
i am crosing my fingers and following your build







oh and try tolearn Sketchup:) preety decent tool for designing and quite easy

[patamos]

Thanks Robert,

Have you heard any news of how Sjang's heater worked out? Any learnings to share?

Yes will learn sketch up one day. For now hands in the mud...

p

[matthewwalker]

Great to see your progress Pat, you are doing nice work. Good job prepping the adjacent structure, looks great from here. I think you may end up wanting to double skin the front as you are thinking. The lack of a metal radiator at the front of the system means you will probably have some fairly high temps, at least in the beginning of the run. I think you could likely build it to where you can burn it before making that decision though, which is what I would try to do.

[patamos]

Thanks Matthew, Robert, and everyone else who is tuning into this thread.  
I once heard a definition of community: com (with, together) munic (service) = service together.  This forum feels like a very authentic expression of that.  And for very good reasons too...

Yes i'll be looking to fire it up, dry things out, patch up cracks etc, and see where the hot spots are.  Will definitely double skin around the down draft chamber.
Today i opted to modify the initial flue run by lengthening it to the end of the bench and then setting a 180 turn.  I was puttering around with all different size bricks and so many tight curves, and realized the work that would go into making all that airtight could be solved with a buried round flue.  
I was also otherwise concerned about how the flue gasses would want to migrate down to the narrow far end if i had left the shorter flue run (ala earlier photos).
Other possible advantages of this approach are that the gasses enter the bell higher up.  The cobb above the galvy flue can readily support the bench surface above; And i can place a 4way elbow (near open elbow in pic) for a clean out with the inside port as a tweakable partial bypass of the longer flue run.

1.5" of clay perlite on the floor with 3/8" cobb plaster on top.  Will probably place a skim of old (stinky) finish plaster once things dry to tighten up the floor and walls    Two bench piers in place.  

Into the rocket core build up soon. 

[patamos]

Well folks, ticking along.  

I made fair progress snaking the flue down the end and back towards the bell today.  And in so doing fed (yet again) my penchant for utilizing scraps of brick, rock, chunks of concrete etc...  All of which i carted over from the island and dropped in their living room, so the de-cluttering felt good.  



4 variably swivelled elbows in a row made easy work of the tight spacing.  



  I had a propane flame weeder on the scene so opted to speed dry the bell faces so i can apply a tight coat of finish plaster sooner than later. I am usually loathe to resort to dyno fuel, but with my heaters, light, drill and cob/mortar mixer already running off a gas generator... the propane seemed an appropriate operation.



I also decided to boost the integrity of my deck support piers by wrapping them in a cob-mesn-cob layup.

Had a nice eureka on a cleanout strategy.  pics of that tomorrow.


well being

pat 

[Robert]

nice... document all of this... you are rocking and doing great service for the community? it is nice to follow such a nicely designed build